PIA09829: Flickering Antares

A point of light flickers behind Saturn’s rings as multiple instruments on
the Cassini spacecraft observe a stellar occultation of Antares (or alpha
Scorpii).

Such observations are designed to understand the fine-scale structure of
the rings. Scientists look at variations in the observed brightness of the
star (whose actual brightness is well known) to determine the opacity of
the rings in different places.

Among other things, Cassini’s prior stellar occultations have been used to
examine density and bending waves induced in the A ring by Saturn’s
various moons.

This view looks toward the unilluminated side of the rings from about 34
degrees above the ringplane.

The image was taken in visible light with the Cassini spacecraft
narrow-angle camera on Jan. 3, 2008. The view was obtained at a distance
of approximately 541,000 kilometers (336,000 miles) from Saturn. Image
scale is about 4 kilometers (3 miles) per pixel.

The Cassini-Huygens mission is a cooperative project of NASA, the European
Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory,
a division of the California Institute of Technology in Pasadena, manages
the mission for NASA’s Science Mission Directorate, Washington, D.C. The
Cassini orbiter and its two onboard cameras were designed, developed and
assembled at JPL. The imaging operations center is based at the Space
Science Institute in Boulder, Colo.